The present invention relates to an apparatus for the input of information.
Various apparatuses have become known for the input of information in conjunction with a screen. Thus, it is known, for example, to point at a screen with a so-called light pen. Located in the tip of the light pen is a photodetector which emits an output signal when the area of the screen covered by the photodetector is scanned by the writing beam of the screen. From the position of said signal with respect to time it is possible to deduce the location of the light pen. Consequently, it is possible, first, to mark an image detail and, second, also to write on the screen.
Further apparatuses for the input of information in conjunction with a screen are so-called touch-screen devices, which are pressure-sensitive or work on a capacity basis. Such devices are presently available from component manufacturers as an addition for picture tubes and flat screens, for example in the catalogue Elektronika, Munich 1995. The measurement of capacity or a change in pressure or resistance in the matrix-addressed plastic sheet applied to the screen is identified by corresponding computer programs and is assigned to the functions and information or program steps placed underneath in masks.
An object of the present invention is to indicate an apparatus for the input of information, said apparatus being able to be manufactured both as a built in (self-contained) apparatus and also as an addition for a screen.
The object of the invention is achieved, in that a raster of light-emitting screen elements is associated with a raster of photodetectors and with a raster of lenses, in that the lenses, the screen elements and the photodetectors are spaced out in such a manner that the emitted light is not-focused and the light emitted by at least one of the screen elements and reflected by an object as said object approaches the apparatus is focused onto at least one of the photodetectors, and in that output signals of the photodetectors are able to be supplied to an evaluation apparatus in order to obtain information on which of the photodetectors are receiving reflected light.
A raster of lenses associated with the raster of screen elements and the raster of photodetectors is provided, the lenses, the screen elements and the photodetectors being spaced apart so that light is not focused. When an object nears the device, light emitted by at least one of the screen elements is focused onto at least one of the photodectors.
The apparatus according to the invention allows specified information entered (to be input) by pointing at it. Input is achieved by the controlled interplay of the image-reproduction function and the image-recording function in the apparatus according to the invention. The selectable information is output in programmed manner through the image-reproduction function of the screen and is shown on the screen as an existing image with different brightnesses and, where appropriate, colors. Using a finger or a reflecting object, the information can be selected by pointing at the area in which the information is displayed and by bringing the finger near to the screen. It is equally possible to use a light-emitting pointer.
The number of photodetectors and light-emitting screen elements may be chosen to suit the requirements. The numbers of screen elements customary in television technology and computer screens, such as 600xc3x97800, may be used for the representation of images to whose resolution an observer is accustomed and which have a high information content. Through a large-area embodiment of the apparatus according to the invention, for example in DIN A4 format, the demands on the lithographic processes and the resolution thereof are lower and, consequently, the costs of the manufacturing machines are relatively low. These can also be implemented through the modification of conventional printing presses.
The phosphors customary in picture tubes may be used as the emitting screen elements, said phosphors being irradiated with electrons by spaced-apart electron sources to which corresponding voltage is applied. The electron sources are preferably field-emitter arrangements which may be produced by corpuscular-beam deposition.
The photodetectors may consist of nanocrystalline composite material produced by corpuscular-beam-induced deposition and described in German patent application 196 21 175.1.
Preferably, it is provided in the device according to the invention that each light-emitting screen element is associated with one photodetector. Depending on the specific requirements, however, it is also possible to employ different numbers of screen elements and photodetectors.
The use of the apparatus according to the invention as a xe2x80x9cflat cameraxe2x80x9d is enabled (made possible) according to an embodiment of the invention in that a converging lens is positioned in front of each photodetector.
A further development of the apparatus according to the invention consists in that, for screen areas each formed by a reproduced mask, in that the intensity measured by the therein situated photodetectors is compared with a known background intensity and in that, when the intensity exceeded the background intensity, it is detected that the object is approaching.
This further development of the invention prevents interference from stray light, which on the one hand, may penetrate from outside and, on the other hand, may be caused by the light-emitting screen elements themselves.
The further development of the invention may preferably be such that the background intensity of the apparatus during times, at which the object is not approaching, is measured and stored in a memory, it being advantageous to provide a computer with screen-comparison routines for comparison and detection.
A particularly advantageous embodiment of the further development of the invention consists in that a memory is provided for at least one mask, the mask preferably being of such design that a minimum light intensity is radiated by those areas of the light-emitting screen elements in which an input is required to be possible. This ensures that, in the area of those photodetectors which are required to detect an input, there is sufficient light for reflection.
In order, however, to prevent the light emitted by the screen elements from likewise entering the photodetectors and interfering with the evaluation process, it may be provided in the apparatus according to the invention that the photodetectors are shielded from the light-emitting screen elements by a light-impermeable layer. Additionally or alternatively, it may also be provided in the apparatus according to the invention that, inside each of the areas, a lower or no light intensity is radiated by those screen elements situated in the direct vicinity of photodetectors from whose output signals information is obtained. Nevertheless, the undirected light propagated from the screen elements ensures sufficient illumination of the object in front of the lenses in front of the photodetectors.
For the purpose of input an additional separation between ambient light and the light emitted by the screen elements may, according to a further embodiment of the invention, be accomplished in that the light emitted by the screen elements is modulated and in that the output signals of the photodetectors are sent through filters which allow the modulation signal to pass.
This measure may, in that different modulation signals and different filters are provided for different areas, also be used for further location selection. In this connection, attention is also drawn to the fact that the apparatus according to the invention is capable not only of evaluating one single approaching object but also of evaluating a plurality of objects.
Furthermore, the apparatus according to the invention may be used not only for the input of information but also for the display of any images and for the recording of images of objects brought in front of the apparatus according to the invention. In another further development of the apparatus according to the invention, therefore, operation in three phases is provided, wherein
during a first phase, the screen elements are energized for the reproduction of an image;
in a second phase, the screen elements emit no light while the output signals of the photodetectors are evaluated for image recording and
in a third phase, the screen elements emit light and the output signals of the photodetectors are evaluated in order to obtain the information to be input.
If the camera function is not required, the apparatus according to the invention may also readily be operated with two phases, namely the first and third phases.
This further development of the invention is preferably designed such that the repetition frequency of the three or two phases is greater than the flicker frequency perceptible by the human eye and/or that the duration of the third phase is considerably shorter than the duration of the first phase. This ensures the flicker-free reproduction of the image, which is extensively free from interference through the mask displayed during the input phase.
The apparatus according to the invention may, on the one hand, be in the form of an independent unit characterized by the apparatus being in the form of a plate-shaped body in which both the light-emitting screen elements and also the photodetectors are located. On the other hand, however, it is also possible to retrofit existing screens by the apparatus being in the form of a plastic sheet, said plastic sheet containing the photodetectors and conductors for derivation of the output signals of the photodetectors and being adapted to be applied to a screen containing the light-emitting screen elements.